11.3: Resistance, Resistivity, and Ohm’s Law

Describe the resistance of an object using physical properties of that object.

Resistance is a measure of the degree to which an object opposes the movement of electric charge.

• The resistance of a resistor with uniform geometry is proportional to its resistivity and length and is inversely proportional to its cross-sectional area

Resistivity is a fundamental property of a material that depends on its atomic and molecular structure and quantifies how strongly the material opposes the motion of electric charge.

• The resistivity of a conductor typically increases with temperature.

Describe the electrical characteristics of elements within a circuit.

Ohm’s law relates current, resistance, and potential difference across a conductive element in a circuit.

• Materials that obey Ohm’s law have constant resistance for all currents and are called ohmic materials.

• The resistivity of an ohmic material is treated as constant regardless of temperature.

• Resistors can also convert electrical energy to thermal energy, which may change the temperature of the resistor and the resistor’s environment.